The invention is related to the field of nanomanufacturing, and in particular to the design and control of flexure-based mechanisms for positioning/fixturing and angular alignment for pattern transfer via stamping and small-scale gap applications in nano manufacturing.
Micro-hot-embossing is a commonly used forming process for polymers. This process involves stamping a patterned tool into a polymer sample to form functional microfluidic channels. A typical stamping cycle includes heating of the polymer sample to high temperatures (above the glass transition temperature), in some cases, up to 200° C. and applying large pressures on the order of 5-10 MPa. Pitch and roll angular misalignment between tool and sample during the stamping procedure can result in errors such as non-uniform depths of the transferred patterns. The non-uniform feature dimensions can critically affect flow rates for the end-user, e.g. a biologist using the microfluidic device.
As an example, in an embossing application requiring 10 μm deep channels to be formed over a 75 mm×25 mm area, a 0.001° (17.4 microradian) tool-sample angular misalignment can result in a 13% variation of depth across the 75 mm lateral span. Assuming other variations are held constant, this height variation corresponds to about a 39% variation in the flow rate across the polymer part, using a simplified Poiseuille flow approximation in the channels. Such a flow rate variation is unacceptable for many precise flow control applications, e.g. microfluidic devices designed for controlled drug delivery.
There are many other exciting applications that require precision positioning and angular (pitch and roll) alignment on a small-scale. Consider, for example, a small gap formed as a separation between two large-area (25 mm×25 mm) optically flat and smooth surfaces, and programmed to vary in the range of 100 nm to 10 μm. Many designs of variable gaps formed between two optically flat and smooth surfaces have been reported. However, none of them address achieving precise parallelism in a plane-on-plane geometry, for example, with flat planar surfaces, and forming the gap at heights of about 100 nm to 10 μm. While coarse adjustments can correct for large initial misalignment between the surfaces, the invention is interested in fine adjustments at a range of ˜mrad, and incremental resolution of sub-μrad for achieving precise parallelism.